Survey of Synergistically Doped CsPbI₃ Quantum Dots for LED Applications

In recent years, colloidal quantum dots (QDs) derived from inorganic halide perovskites have shown great promise in optoelectronic applications. Despite their promising optical properties, the full potential of CsPbI 3 QDs is significantly undermined by high surface trap densities and poor environmental stability. To address these challenges, this research focuses on an innovative approach involving synergetic Co 2+ doping of CsPbI 3 QDs and I – /Cl – ion passivation. Co 2+ doping is achieved by utilizing various dopant sources such as CoI 2, CoCl 2, and mixed CoI 2 /CoCl 2 . The anions from CoCl 2 and CoI 2 occupy iodide vacancies, thereby reducing nonradiative recombination. The optimized composition, CsPb 0.95 Co 0.05 I 3 QDs with mixed CoI 2 /CoCl 2 doping, exhibits exceptionally low trap density and superior stability. The superior efficacy of mixed doping compared to sole CoCl 2 doping suggests the complementary action of I – ions (from CoI 2 ) along with Cl – ions (from CoCl 2 ) in passivating surface defects. Optimized CsPb 0.95 Co 0.05 I 3 QDs demonstrate a significant boost in photoluminescence (PL) performance and stability, achieving an exceptional 98.86% PL quantum efficiency while maintaining stability for over two months under UV light exposure. Integration of the optimized QDs into LED devices yields an outstanding external quantum efficiency (EQE) of 34.6%, showcasing their promising potential for efficient lighting applications.